Advanced Arms Training: Brachialis and Brachioradialis

Medical illustration of the brachialis arm muscle
Brachialis. SomkiatFakmee / Getty Images

The following are some bodybuilding training techniques for the elbow flexor muscles, brachialis and brachioradialis.

The Brachialis

The brachialis is the primary mover during the preacher curl. But, what is the brachialis and where it is located? More on that in a second, but first here's an interesting tidbit: the brachialis has a larger cross-sectional area than the biceps. That's right, the brachialis is the larger muscle, at least in the average person, which should be enough of a reason for you to do brachialis-specific exercises.

Many trainees don't focus on their brachialis simply because they are not aware of the muscle. It is not too apparent from the outside because it is located underneath the bottom half of the biceps brachii. The brachialis originates at the lower half of the humerus, or upper arm bone, and inserts at the ulna, or outer forearm bone. The brachialis therefore only crosses the elbow joint, so it is a mono-articulate muscle. Your shoulder and forearm positions do not influence its recruitment. And, your brachialis is always recruited when you flex your elbows. Because of this, it referred to as the workhorse of the elbow flexors.

Exercising the Brachialis

Anytime you do the biceps curl or any other type of curl exercise, you will working the brachialis. But, to maximize the muscle's development, you should do two types of exercises: one in which your shoulders are flexed and one in which your forearms are pronated.

The more you flex your shoulders, the more brachialis, and less biceps, you recruit. Preacher curls mainly work the brachialis, and they are a good exercise for this muscle. However, they still involve a bit of biceps brachii involvement, especially the longer head.

A better exercise for the brachialis is the overhead brachialis curl.

By fully flexing your shoulders to the point where your arms are in an overhead position, you will take the biceps out of the movement, forcing the brachialis to work even harder. You can do this exercise using the lat pulldown machine. Use a cable curl bar rather than the long lat bar.

Another exercise you can do for the brachialis, without any biceps brachii involvement, is the reverse curl. So, instead of supinating your forearms and grasping the barbell, dumbbell, etc. with an underhanded grip, you should pronate your forearms and utilize an overhanded grip. Doing so will cause the biceps insertion tendon to wrap around the radius, thus not allowing it to contract. And, once again, this forces your brachialis to contract more forcefully.

The Brachioradialis

The smallest of the three main elbow flexors is the brachioradialis. This mainly lies over the forearm. It inserts at the lateral supracondyle ridge the humerus and inserts at the styloid process of the radius. The brachioradialis is a bi-articulate muscle because it crosses the elbow and radioulnar joints. It acts as an elbow flexor and a forearm semi-pronator, meaning it can bring the forearm to a neutral position halfway in between full supination and full pronation.

Exercising the Brachioradialis

Similar to the brachialis, the brachioradialis is recruited anytime you flex your elbows. However, the muscle is best worked when the forearm is in a semi-pronated position, such as when doing hammer curls. The aforementioned reverse curls also work the brachioradialis to a larger degree due to the fully pronated forearm position, but the brachialis is the primary mover of the exercise.